1. Field of the Invention
The invention relates to equipment for applying coatings to surfaces of products, and more specifically, it deals with apparatuses for hot gas spray deposition of coatings on products in the form of bodies of revolution.
2. Description of the Related Art
Known in the art is an apparatus for applying coatings to products in the form of bodies of revolution (SU, A, No. 761023), comprising a chamber, a pair of means for rotating the product having drive rollers engageable with the product surface, transfer rollers for axially moving the product, and a spray gun. One of the means for rotating the product is mounted for movement axially along the product. Each means for rotating the product has an individual power actuator for lifting the product in the form of a hydraulic cylinder, and the transfer rollers are provided with a rotation drive. The apparatus is designed for the deposition of coatings on large-size products and in particular, on large-diameter pipes which must be installed at a coating station using special handling means.
A product having its surface preliminarily prepared for coating application is placed on the transfer rollers, the drive of the transfer rollers is switched on, and the rollers move the product towards a stationary means for rotating the product and stop. Subsequently the other means for rotating the product are moved in the same direction and stopped in the zone of the rear end of the product. The power actuators are then turned on for lifting the product which is raised from the transfer rollers, the drives of the product rotation means are then switched on, and a coating is applied to the product surface.
Since the product is rotated on the rollers of the means for rotating the product during coating deposition, a layer of coating cannot be applied to that part of the surface of the product which engages the rollers during rotation. The stationary transfer rollers are in the spray gun zone and under it during coating deposition so that a layer of coating is also applied to their surface, the coating being applied only to that part of the working surface of the roller that faces towards the spray gun. This results in local enlargements being formed on the working surface of the transfer rollers to lower reliability thereof in operation. During the axial movement of the product along the transfer rollers the surface of the product is impaired after preparation for application of the coating. As preparation for application of a hot gas spray coating involves imparting roughness to the surface with a pre-set height of crests and also elimination of grease films on the surface, the movement of the product on the transfer rollers results in the removal of the crests of the roughness and in the reappearance of grease spots on the products surface. This negatively affects quality of deposition of a hot gas spray coating on the surface.
It should also be noted that the provision of a pair of hydraulic power actuators for lifting the product and a drive for rotating the transfer rollers makes the apparatus rather complicated.
Known in the art is an apparatus for a hot gas spray deposition of coatings on products in the form of bodies of revolution WSP manufactured by PLASMA TECHNIK AG.
The apparatus comprises a chamber in which there is a base supporting a headstock having a spindle and a tailstock having a revolving center coaxial with the spindle, and a spray gun mounted for movement on the base. The tailstock is mounted for movement axially along the spindle. The revolving center of the tailstock has a manual drive for bringing it towards a center hole of the end face of a product and for retaining its axial position.
The product is manually installed in the head stock spindle, the revolving center is then inserted into the center hole of the rear end face of the product, and this axial position of the revolving center is retained. The spindle rotation drive is switched on, and the spray gun moving along a guide member applies coating to the rotating product.
The prior art apparatus has limited production capabilities as a product of up to 20 kg only can be manually installed. If products weighing more than 20 kg or products that cannot be manually installed are installed on this apparatus their surface prepared for coating application may be impaired so as to result in impaired quality of coating.